Bacterial and fungal infections have become a worldwide problem that threatens human health and is highly concerned in the global health care industry. One of the important means to solve the problem of bacterial or fungal infections is to impart antibacterial properties to the surface of a material or a product, so as to prevent bacteria or fungi from growing or proliferating on the surface of the material or the product, or even to kill the bacteria or fungi already present on the surface. The usual solution is to adhere or anchor antibacterial components or materials to the surface of the product by means of spray coating and/or chemical bonding, thereby achieving the antibacterial properties. Known antibacterial materials are widely applied on ceramics, glass products, plastics, rubbers, fibers, papers, painting, etc., such as household appliances, furniture, janitorial supplies, food packages, and clothing. At present, world-wide antibacterial materials may be classified into four categories: (1) inorganic antibacterial agents, such as nano-titanium dioxide, nano-silver, nano-copper, and ions thereof; (2) organic antibacterial agents, such as quaternary ammonium salts, alcohols, haloamines, biguanides, and thiazoles; (3) polymeric antibacterial agents, such as polymeric quaternary ammonium salts; and (4) natural and modified antibacterial agents, such as chitosans and sorbic acids.
In order to impart antibacterial properties to the surface of the material or product, the most common method is to cover the surface with a coating containing antibacterial agents (such as nano-silver, nano-copper, and ions thereof, or other antibacterial agents), and/or nano-silver, nano-copper, silver ions, copper ions, other heavy metals. Relying on the slow release of metal ions into the ambient environmental, the purpose of bacteriostasis or sterilization is thereby achieved. However, the antibacterial capability of these metal ions gradually reduces over time until the antibacterial capability is completely lost, meanwhile, microorganisms may be induced to mutate by the metal ions, thus increasing the probability that the microorganisms develop drug resistance. In addition, harmfulness of nano-materials has gradually been recognized and paid attention by human beings.
The organic antibacterial compounds, such as quaternary ammonium salts, alcohols, haloamines, biguanides, and thiazoles, bear the characteristics of taking effect in short time, and extinguishing bacterias efficiently. This category of antibacterial agents mainly includes quaternary ammonium salts and quaternary phosphonium salts. Generally, cell walls of bacteria are negatively charged, and ions, such as quaternary ammonium salts and the quaternary phosphonium salts, are positively charged. The quaternary ammonium salts with positive charges are liable to be absorbed by the bacteria, penetrating the cell walls after approaching the bacteria, being bonded to the cytomembrane, and disrupting the composition of the cytomembrane, which results in leaking of intracellular materials and eventually death of the bacteria. However, the chemical activeness of the quaternary ammonium salts, which exist substantially in a free state during use and have high toxicity and strong irritation, is low. When used as antibacterial agents, the quaternary ammonium salts have poor heat resistance, tend to migrate and can be washed easily. Moreover, the quaternary ammonium salts tend to enrich on skins of human bodies gradually, thus a long-term use of quaternary ammonium salts may cause microorganisms to mutate, resulting in drug resistance for these microorganisms. Meanwhile, the organic antibacterial agents have poor heat resistance, thereby limiting their use range thereof.
The polymeric quaternary ammonium salt antibacterial agents can overcome problems of micro-molecule antibacterial agents, such as being volatile, unworkable, chemically unstable. Moreover, the polymeric quaternary ammonium salt antibacterial agents exhibit good antibacterial activeness, and are less permeating, which helps drawing attention of the people. At present, however, the unimmobilized polymeric antibacterial agents also exhibit drawbacks such as high leachability and lack of sustainability, which presents pressure to the ambient environment as well.
The natural antibacterial agents are derived from extracts of natural plants, animals or minerals, whose main antibacterial mechanism is similar to that of the organic quaternary ammonium salts, but are less effective than the organic antibacterial agents, and products of the natural antibacterial agents are not yet mature. Another drawback of the natural antibacterial agents is that they are not suitable for mass production, so that their application thereof is limited.
Therefore, there is a need to develop and prepare antibacterial agents which are green, immobilizable, and durable.